Power hammer



Oct 20, 1931- .1. H MEEKER ET Al. 1,827,877

POWER HAMMER Filed March 6, 1929 JOHN H. MEEKER, OF SOMERVILLEfNEW JERSEY, AND ERIC K. SKONBERG, 0F

BROOKLYN,

NEW YORK j POWER HAMMER -appiiavcion mea March le,

- of the portable type which have serious faults of operation, or are of complicated or intricate construction, particularly in hammers employing vacuum principles of operation.

- Among the faults of operation are those due to objectionable rattling of the parts, especially the reciprocating parts, caused by lack of proper cushioning and in some forms to the increase inthe number of parts employed in effecting variation of the vacuum during the lstrokes of the active parts. Also there are faults involving danger of injury to the hands of the operator by improper arrangement of parts. And there are other faults of construction due to increase ofthe number of parts to secure greater facility of manufacture of certainparts.

rlfhe main object of the present invention is to provide a power hammer embodying air influenced devices in which the parts are few vand simple to manufacture. Another object is to provide an improved article of this class which -employs pneumatic' means to modify the operation of certain reciprocating parts and to minimize the rattle of moving parts, and a further object is to improve the means for giving working strokes of varying force from light cushioned blows to sharper blows of greater force and without undue heating of parts. Another object is to provide an improved implement which tends to prevent injuries to the handsof the operator.

Among the faulty implements above-mentioned are certain ower hammers having barrels provided with thin tubular linings 1929. Serial No.. 344.711..

forced into the main barrels. ln our improved construction we avoid such thin tubular linings and provide a barrel in which the integral central bore can be finished with great accuracy by grinding. Also certain hammers f have internal flanges in the barrels which necessitate the use of the tubular linings above referred to or to very expensive grinding operations. Among the faulty structures likely to injure the hands of the operators are those having sliding inner sleeve construction in which the lower parts have recipricating shoulders or collars which move toward and from shoulders or collars on the outer parts of the barrels. It is obvious that such construction will sooner or later result in bruising the hands of the operators. In regard to the hammers employing vacuum principles, some parts of either the working or retracting strokes are found to develop a rattle in such implements on account of the rapid change in the application of power as will be clear on study of suchhammers. Also cerl tain vacuum hammers have a discharge of air through ports in the casing which discharge frequently becomes mixed with oilboth-of which features are highly objectionable.

ln our improved .implement we have overcome the above objectionable features and have produced a safe and quiet running article, that is simple and economical to manufacture-f Such being the case we are able to make the parts of better quality than could .be'done at thesaine price for the more com-l plicated articles. And also for the reason that we are able to provide hardened and ground steel parts in place of parts not hardened and ground, or which are merely ground and not hardened. i

The means we prefer to employ for accom- S5 plishing the above-named o jects together with other novel and advantageous features which will appear hereinafter, are illustrated in the drawings accompanying and forming part of this specication," and in whiclut@ 'being in opposite positions to t Figurey 1 is a longitudinal section of one form of our improved power haer taken on the line 1- -1 of Fig. 2.

Fig.' 2 is a view taken partly in side elevation and partly in longitudinal section along the center lineot the'barrel and at right angles to the section in Fig. 1 certain parts hose of Fig, 1.. Fig. 3 is a view similar to Fig. 2 but with Vcertain parts in another position.

Fig. 4 is a longitudinal section of a portion of the barrel with certain parts in still another position.

Fig. 5 is a detail side elevation of the body of the barrel.

Fig. 6 is a transverse sectiorrof the same i taken on the line 6-6 of Fig. 5.

Fig. 12 is a detailtl/ongitudinal section of the plug or lower barrel bushing, and

Fig. 13 is a plan of the same.

Like characters of reference refer to like parts in all the fi ures of the drawings.

Referring tot e drawings, the numeralI 1 designates the housing or head of theimplement and which is provided with an opening 2 which ispreferably Vscrew-threaded and 1s adapted to receive an annular member 3.

f rlhere is a projection or hub 1m formed opposite the openingv 2 substantially on the same th vh h'ch the ams and has an Openmg mug W 1 R90 and 1ts grooves or passages.

drive shaft 4 is placed `and journaled preferably in a ball bearing 5.

The housing 1 has also fa crank chamber 2n in which is placedthe rotary member or drive plate 6 'having a weighted balance 6:12 at one sidel and at the other is an eccentric or crank pin 'w oil center of said shaftl4. 'lhere is a connecting rod 7 pivoted on the eccentric pin at one end and at the other end is connected to the piston 8. by the ball joint 7 m. The said piston 8 is Vfitted to the bore 9.1: of the barrel 9 which at its upper end is externally- `screw-threaded at 9mm and secured in the iIL- ternallyscrewthreaded opening ln of the housing 1. The annular member 3 is provided with an annular recess`3m in which is placed a body 3u: of fibrous material such as felt, the inner face of which is disposed in juxtaposition to the end of the pin 6w. The fibrous ma# terial is adaptedto be saturated with oil which can` be replenished through the oil hole 3mm, closed by the screw 31m so that the crank pin 6w/.is adapted to take on oil from the fibrous portionfw when the oil supply in the crank pin chamber becomes low. f

. maaar? Also in the bore 9m of the barrel 9 is adoating plunger' 10 which has a reduced portion 10m at its upper art which is adaptedto enter the recess 11 ormed in the lower end of the piston 8. The lower end of the barrel 9 is internally screw-threaded at 9a and adapted to receive two bushings, .the upper one 15 of which has a central opening 15m, a spring recess 15a in which a coiled spring 16 is placed, and a lower recess 15p in which a washer or collar 13 is located and on which" the lower end of the spring 16 rests, while its upper end bears against the shoulder ly. The spring 16 acts through the washer 13 lllpon the shoulder 17m ofA a tool or tool holder the reduced upper end 17mm of which is adapted to make contact with the lower .end of the plunger 10. The barrel 9 is intwoparts, the first or main part 9m is formed with a chamber indicated b 90, exterior to the bore 9m and-extending a ong the same. Preferabl there are upper air ports 18, interme iate air ports 20, and lower air ports 21 connecting the bore 9m .with said chamber 90. ln the form herein shown said chamber has annular passages or grooves 18:15 and 21a: near or at the ends of the chamber and with a lthird groove or passage 20m between them.

The annular grooves are also shown as connected by longitudinal passages such as the longitudinal grooves 92, with ribs 92a between said passages forming the periphery of the barrel part 9a. The air ports 18, 20

nular grooves or passages 18a/1, 20w and 21m respectively. The lirst or .main barrel part 9a andthe chamber 90 therein are covered by the second barrel part or sleeve 9b, which in eectforms the outer'walls of said chamber The sleeve 9b is secured in position by lmeans of the interior flange 1902 in its upper part, said flange being clamped between the shoulder 9o on the upper part ofthe barrel and the lower face of the housingopening 1n. The chamber 90 orlsystem formed by the passages 90, 18m, 20a: and 21m, and ports 1 8, 20 and 21 is closedto the flow of air except at said ports 18, 20 and 21.

All the Orts 18 are in alinement with each other horlzontally aty the groove or passage 18m, all the ports 20 are alined horizontally at the passage 20,land the ports 21 are similarly alined at the passage 21m so that the piston 8 and plunger-10 will be influenced in a balanced manner by the .pneumatic pressure through said ports. The air pressure in said passages and ports will normally be uniform throughout the-system except as modified by the .entrance or egress of air through said ports.

The shaft 4 at its right hand end is screw- Land 2l lie in or are connected with said anlio threaded to be received within a sleeve 2 2 which `also receives the screw-threaded end Preferably there is a portion of felt 26m tov prevent the escape of oil from the interior of the housing 1 into the flexible shaft casing.

To properly oil the hammer, the housing or head 1 is supplied with a quantity of oil through the oil hole 3mm, and the hammer is then turned upside down while running and .l oil is dropped into the barrel between the ,end of such a down stroke.

tool holder 17 and the hole in the bushing 12 so that it will run into the bore 9x' and through the air ports into the chamber 90.4

' will be reduced to a minimum.

Fig. 1 illustrates the positions of the vari-- ous parts at the commencement of a down stroke of the piston but in which no work is being done by the tool or holder 17. Fig. 2 illustrates the positions of the parts at the Fig.- 3 illustrates an intermediate position of the piston and a position of the plunger suitable for performing working strokes on the tool or holder 17. Fig. 4 represents a similar .position of the plunger but with the piston in its lowermost position. Fig. 9 represents the positions of the lower end of the piston and the upper end of the plunger when strokes of the greatest force are being given.

The operation of our improved power hammer is a follows The positions of parts in Figs. 1 and 2 are taken during the time when the implement is doing no work but show the piston, connecting rod and eccentric or crank pin in two different positions, Figfl showing the uppermost position of said parts and Fig. 2 the lowermost position of the same. When the piston 8 moves downward past the ports 18 and closes the same, it compresses the air in the bore 9m between the piston and the plunger 10. However, by reason of such compression some of the air passes out through the ports 20 into the passages or grooves 20w and v90 and also into the ports 18 and 21. Thus the pressure is increased in said ports and passages, all the parts fitting closely enough and there alsobeing oil films between surfaces of the parts so that practically no air leakage occurs.

During all this time the plunger 10 is in its lowest position relatively to the barrel and together with the shank of the tool or tool holder 17 is in the position indicated in Fig. 1. In order to do work on the tool 17 the operator presses down on the implement, so that relative movement takes place between the barrel 9 and the plunger 10 and tool shank 17 as represented in Figs. 3 and 4. The plunger 10 thus closes the ports 20, so that as the piston 8 descends it increases the pneumatic pressure on the end of said plunger suiiiciently to produce a working stroke of the same which in turn is communicated to the tool shank 17. Fig. 4 illustrates the positions of the piston, plunger and tool shank at the lower end of the piston stroke when the implement hasbeen moved down an amount equal to about twice the diameter of one of the ports 21.

When the tool shank 17 and plunger' 10 are in their highest position in the bore 9m, at the lower end of the piston stroke, the piston and plunger will come together substantially as illustrated in Fig. 9 and the air contained in the bore 9x between the piston and plunger will be compressed into the small space 91 between the end of the piston and the shoulder on the plunger and also an infinitesimal amount in the recess 11 between the end of the plunger and the end of said recess. Duri-ng this time the air in the port system formed by the passages grooves or passages 18m', 20x, 21.12, 90' and ports 1820 and 21 remains slightly above atmospheric pressure or substantially at the pressure existing in the bore 9m at the instant the ports 20 were closed by the relative movement between the same and the plunger 10. d

In the positions of the piston and plunger shown in Fig. 9 the implement is delivering its sharpest and most forceful blows, while with the plunger in the position of Fig. 3 it delivers its lightest blows. The intermediate positions between these two will permit variations in intensity all the Way from the lightest blows to those of greatest force, the relative cushioning effect .due to the trapped compressed air being less and less as the maximum force blows are approached.

When the piston 8 and floating plunger' 10 are in their highest'position, they tend' to separate from each other because the compressed air in the recess 11 tends to force them apart, and part of such air then flows through the port or ports 18 into the chamber 90. The bottom of the plunger l() is under substantially the same pressure as that of the chamber 90, which pressure assists in raising the plunger. The pressure on the top of the plunger in Fig. 1 i's substantially the same asv that on the bottom and whenever the motor or other power for driving the device is stopped the plunger finally assumes the position of Fig. 1. When the parts are ascending in the relations shown in Fig. 4, friction between the plunger 10 and the bore 9.1', together with the expansion of the compressed air in the recess 11 tend to se arate the two ports 18, which permits the air from the.

g chamber 90, this eing somewhat above atmospheric pressure, to assist in orcingdown the plunger so that the piston and plunger then separate. When air comes through the port or ports 18 from the chamber 90 into l@ the bore 9m, some oil will also pass into said bore, thus insuring more thorough oiling oi the piston 8 and bore 9m under the same and then passing down to oil the plunger 10 and the bore around the same.

passage and port systemthe air therein is prevented from falling below atmospheric pressure so that suction edects in the up strokes-are reduced to a minimum. This 20 tends to keep down the shocks and noise of operating parts as these parts are cushioned to the maximum amount for the type of im.- plement. 'lhe closed arrangement of said system also' tends to prevent the undue escape of oil-trom the implement so that the various parts thus have better lubrication and do not become excessively heatedby friction with each other.

rl`he interior of the housing is partly or i 3@ wholly lilled with oil at the commencement ot operation and is practically closed to the 4outside atmosphere and it has no direct communication with the air in the bore 9m or in Y the passage and port system. Lubrication of the piston 8 and plunger 10 is e'ected by the slow downward iow of oil iromthe housing 1. 'llhe shank 17m of the tool or holder 17 and the washer 13 together with the bushing 15 and nut 12 are lubricated by the further 0 downward movement of o1l.

i air in the passage system andpartly carried away by radiation. 'lihe said passages 90 18m, 20wA .and 21m are made sufliciently large so that the heatof the air therein'will not be unduly increased by air flow-therethrough and the total heat due to friction of metal -partsand compressed air is such that the casing 19 does not become uncomfortably warm to the hands ofthe operator. l p

lt will be clear from the foregoing that t0 the im lement has a minimum numberot parts or the edect obtained, that undue v heating of the implement is prevented and by reason of the exterior barrel construction the implement does not tend to injure the hands f of the operator. Y.

By reason ot the closed arrangement or the y naamw plunger slidable within said cylinder between said piston and said tool element and adapted to be forced outward by outward move-` ment ot said piston for impact with said tool.

element,rsaid cylinder having a pair ot ports one ot which is disposed to `relieve the air pressure between said piston and said plunger when the plunger is substantially at its limit of outward movement, and the other of whichis disposed to admit air between said 5@ piston and said plunger when the piston is substantially at the extreme end oi its inward stroke.

2. A power hammer comprising a cylinder, a piston reciprocal within the inner end por- 35 tion of said cylinder, means lor reciprocating said piston, a reciprocal tool element, a plunger slidable within said cylinder between said piston and said tool element and adapted to be :forced outward by outward movement t@ ot said piston tor impact with said tool element, said cylinder having a pairot ports one of which is disposed to relieve the .air pressure between said piston and said piling er when'the plunger 1s substantially at its 95 limit ot outward movement, and the other of which is disposed to admit air between said piston and said plunger when the piston is substantially at the'eatreme end ont its inward stroke, and means providing a closed ttt chamber connecting said ports with one another. l /1 3. Apower hammer comprisinga cylinder, a piston reciprocal within said cylinder, a drive shaft, a crank and itman rive conneet-ion between said sha' and said piston, a reciprocal tool element, and a plunger slidable within said cylinder between said piston and said tool element adapted to be iorced outwardby outward movement ot said pisll@ ton for impact with said tool element, said cylinder having a pair ol ports one ot which v is disposed to relieve the air pressure between said pistonand said plunger when the plunger is substantially at its limit of outward im movement, andthe other of which isdisposed f in the plane of the outer end of the piston Awhen the'latter is substantially at its lt `of inward movement with the o eratingA crank thereof substantially onl dea oenter.` lao 4i. A power hammer comprising a cylinder,

a piston reciprocal within said cylinder, a drive shaft, a crank and itman drive con= nection between said sha t and said piston,

a reciprocal tool element, a pluncer slidable E25 Awithin said cylinder between saidpiston and said tool element adaptcdrto be forced outward by outwardmovement ofsaid piston for impact with'csaid'tool element, said cylinder having a pair of ports one otjwbich is ist disposed to relieve the air pressure between said piston and said plunger when the plunger is substantially at its limit of outward movement, and the other of Which is disposed in the plane of the outer end of the piston when the latter is substantially at its limit of inward, movement With the Operating crank thereof substantially on dead center, and means providing a closed chamber Connecting said ports With one another.

Signed at New York, in the county of New York and State of New York, this 28th day of February, 1929.

JOHN H. MEEKER. ERIC K. SKONBERG. 

